The dishwasher is designed to wash a high volume of plates, cups, cutlery and crockery in a consistent way that is unaffected by human error.
Water is filled into the wash tank
- A detergent is run into the machine through a chemical dispenser.
- Crates are provided to place pre-washed crockery, glasses and cutlery into the machine.
- The machine runs through the wash cycle in a preheated wash tank that should be operating at between 50 – 65 ° C (131 – 149° F).
- Then the cycle changes over to a rinse:
The rinse cycle has 3 functions
- Rinse off the detergent
- Dry the items to prevent water build-up
- Sterilise the equipment in the machine (+80° C +176° F)
During the rinse cycle, a rinse aid is added to the machine.
Despite its name, the rinse add does not “aid in the rinsing” process. But rather allows water to run off the equipment so that they dry properly.
Remember from our article on bacteria. That bacteria need moisture to grow and survive. Therefore if these items are completely dry, there is less chance of bacteria surviving.
These are the basics of how the machine works. It’s somewhat important to understand that the machine has two separate heating systems.
One is for the washing which is heated with an element and the second system essentially superheats water running through the two heaters to get temperatures above 80° C (176° F).
The dishwasher in the kitchen can be a very efficient machine to us in the commercial kitchen. Crockery, glasses and cutlery can be washed in the wash and rinse basins by hand. Yet, there are definite benefits to using a machine for this purpose, rather than washing all equipment together.
What are the benefits of using a dishwasher in the kitchen?
- Energy efficiency: Water-efficient models use an average of only 15 litres (4 Gallons) of water per wash, 32-39% less than standard dishwashers, saving up to all 4 000 L (1,000 Gal) of water per year. Commercial dishwashers vary in their water use from 10 – 30 L (2.5 to 8.0 Gal) of water per minute, depending on the type of dishwasher. Compared to manual washing an average of 30 L (8 Gal) for washing and 30 L (8 Gal) for rinsing. There is a clear benefit on water saving and energy cost on heating the water.
- Efficient cleaning: washing and rinse of large volumes of items.
- Time: being able to cycle through a high volume of items as compared to manual washing.
- Extra sanitation: From our tests, it is more likely to have continued contamination through the manual washing process compared to the efficient washing and high temperature of the dishwasher in the kitchen.
One argument we often hear, is the start of cost on purchasing the machine, the regular maintenance cost of chemicals etc.
These are fair complaints, especially when considering the once off cost of purchase for these dishwashers in the kitchen.
However, consider this:
To effectively wash glasses, these items need to be washed separately from pots and pans due to the grease build-up. Although 55° C (131° F) rinse water is effective in killing bacteria. It simply cannot compare to +80° C (+176° F).
In our experience, the rinse water is difficult to maintain even at 45 ° C (113° F). This means water build-up and the unsightly smudging water stains. This very likely then means that you need staff to towel dry the glasses, which presents cross-contamination concerns.
Installing separate wash and rinse basins for crockery, cutlery and glasses is less costly. However, you also need to consider the strain on the boiler, which means electrical costs. The dishwasher machine simply uses less energy to clean. Installing automated chemical dispensers to the machine for wash and rinse cycles, and having these maintained by the chemical supplier will help manage the chemical consumption.
The above complaints usually come from kitchens where machine are not well maintained and the dispensers are never services by the supplier.
How to use the dishwasher correctly:
- Always switch on the dishwasher beforehand, and run the machine at least twice before starting the first wash for the day. This is to ensure the dishwasher is correctly heated and there is sufficient detergent in the machine.
- Place each item in the correct washing crate. This means cutlery into baskets, glasses into slotted crates.
- Always pre-rinse items before stacking into the machine.
- As tempted as one might be to rush through the dirty items, never over-stack the crates.
- Run through the machine and allow a full wash and rinse cycle.
- If the machine is fully operational, the items will be too hot to handle. Allow the items to cool and dry.
- Pack all items neatly and away from any opportunity to cause cross-contamination.
- All hollow items should be placed upside down to prevent the above concerns.
Food Safety @ Home Tips
You might even take the good habits you learn from loading a commercial dishwasher to your home kitchen. Keeping hollow items upside down, pre-rinsing or pre-scraping, placing cutlery in the dedicated baskets, and not overloading are four pieces of advice that apply consistently across all types of dishwashers.